Booting the FPGA & Schematization of the USB3320

For the past days, I have been working on the schematics of our ULPI transceiver, the USB3320 and when my colleagues were working on other parts of the schematics, I had to focus on other stuff such as making our SOM work and improving our system architecture.

Making our Cyclone V SOM work was a breath of air compared to the schematic part. Following the Quick Start Guide of our development kit, I had to make sure the jumpers were setup correctly (and they were – not sure if it was the factory default or if Alexis did his magic before giving us the devkit) and configure the UART0 interface. Once everything was set and connected on /dev/ttyUSB0, I simply plugged in the devkit and it booted correctly.

You can see the booting log on this pastebin post

As we would like to be able to use Wi-Fi USB dongles, we are currently adding host USB 2.0 support. Unfortunately, we must use the ULPI interface to communicate with our USB devices. Thus, we have to use a ULPI-USB transceiver.

ULPI works with a 60MHz clock and I am unsure for now if our FPGA can generate such an accurate reference. However, the USB3320 can work with a external oscillator and it has its own PLLs to generate a 60MHz clock from a 12MHz reference clock.

Below is a work in progress of the schematic of the USB3320 in our system. It also includes a Linear Voltage Regulator as the transceiver also needs a 1.8V DC supply. 

What is definitely missing are the appropiate capacitors and resistors that I have not added everywhere yet.

USB3320 Schematic (WIP)

2 Replies to “Booting the FPGA & Schematization of the USB3320”

  1. Note for the random passer-by, these acronyms might not be so straight forward:
    – ULPI: UTMI+ Low Pin Interface
    – UTMI: USB Transceiver Macrocell Interace
    Keep up the good work guys 😉

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